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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .shadow1{
      width: 200px;
      height: 200px;
      border-radius: 50px;
      box-shadow:  inset 10px 10px 50px rgba(100, 100, 100, 1),
      inset -10px -10px 50px rgba(100, 100, 100, 1);
    }
  </style>
</head>
<body>
  
  <div class="shadow1">
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</body>
</html>